Elevated occupational exposures to crystalline silica dust can result from construction activities in which concrete and stone are used. In particular, the use of power grinding, drilling, and cutting tools by masons and concrete finishers can result in unsafe exposures to silica dust. The main objective of this project is to evaluate commercially available, but untested, masonry tools to determine their effectiveness in reducing dust emissions. A series of semi-controlled experiments will be conducted to determine the effectiveness of water suppression and local ventilation control techniques when used with 6 different classes of hand-held masonry power tools. The most promising tool/control combinations, as determined by initial semi- controlled experiments, will be further tested during use at a construction site to evaluate how non-ideal conditions affect tool/control performance and to assess worker and management acceptance. The identification of effective control strategies for reducing silica dust exposures will provide practical guidance to masonry construction industry and reduce the possibility of occupational lung disease related to silica exposure in this industry.